Karin,
You mentioned due to time restraints, you send your finished paintings out to be professionally photographed. Can you elaborate on that? Photo lab, or photographer, reasonably priced?
Mike,
You mentioned that you sent yours to a photo lab and got great results. I've called around different photo labs here in Las Vegas, and they say they only process negatives. I've been checking into scanning, but no one here has any scanners that big. One lab said he'd photograph the painting for like $100, then send that to be scanned. That defeats the purpose anyway.
Here is an article on scanning oversize paintings I found interesting. I may try it.
http://www.artcafe.net/artcenter/digital/feat7s.htm